Hopefully, they'll view it as just another Protege. The insurance for the WRX is around the same as the Honda Civic SI, so if you can afford the SI then you should be able to afford the WRX. I don't think $21k would be over priced for the MS-P, just remember that it is a well rounded limited edition turbo'd car. If you take a look at previous turbo'd vehicle MSRP's, you start to get the idea of where the pricing might be. Just like accounting guys, all the numbers are there you just have to put them together.
98' Eclipse GS-T $23,645
96' MR2 Turbo $25,318 (over priced)
02' GTI 1.8t $20,535 (cheaper, but it doesn't have the same goodies as the MS-P)
02' WRX Wagon $23,495
After seeing those numbers, you begin to catch my drift. $21-$22k would be a great price for it, at least in my opinion it would.